The present invention is directed generally to cartridge tape players, and more particularly to a two-channel and four-channel cartridge tape player in which the changeover of two-channel play to four-channel play or vice versa is automatically made in accordance with which one of two-channel cartridges or four-channel cartridges is inserted therein.
For the better understanding of the features and advantages of the present invention, two-channel and four-channel cartridge tape players now commercially available, will first be described with reference to FIG. 1. FIG. 1 is essentially a circuit diagram of a two-channel and four-channel cartridge tape player and illustrates only the circuit arrangement for an understanding of prior art.
In the prior art devices, when a two-channel tape cartridge is inserted into the tape player, a multi-pole change-over switch SW1, which is illustrated as a ganged slide switch, determines which one of a two-channel or four-channel cartridge is inserted therein, and is switched into the state shown in FIG. 1. Thus the tape player starts to play the two-channel tape cartridge. Assuming that a block of magnetic head H is at higher level being elevated by a head shifting cam 1, the signal recorded on the first recording track 1' is picked up by a magnetic head H1 and reproduced through both speaker SP.sub.1 and SP.sub.2, and the signal recorded on the fifth recording track 5' is picked up by a magnetic head H.sub.5 and reproduced through both speaker SP.sub.3 and SP.sub.4. When the full length of the first and fifth recording tracks 1' and 5' (Channel-1) are finished playing in the two-channel stereo mode, an electrically conducting spot adhered to the tape short-circuits contactor 3 to cause means for rotating the head shifting cam 1 such as, for example, an electro-magnetic solenoid 2 to rotate one step, so that the block of magnetic head H descends to its next lower level. The descending action of the head block H causes a switch 3 to close. Thus, the second and sixth recording tracks 2' and 6' (Channel-2) are picked up by the magnetic heads H.sub.1 and H.sub.3 respectively and reproduced through the speakers SP.sub.1, SP.sub.2 and SP.sub.3, SP.sub.4. When the full length of the recording tracks 2' and 6' are finished playing, the electrically conducting spot short-circuits the contactor 3. At this time, because the switch SW.sub.3 is closed, a relay RY is energized to switch another changeover switch SW.sub.2 to cause magnetic heads H.sub.2 and H.sub.4 to come into operation. The solenoid 2 is energized again to rotate the head shifting cam 1 so as to shift up the head block H back to the original higher level. Thus, signals recorded on the third and seventh recording tracks 3' and 7' (Channel-3) are picked up to play by the magnetic heads H.sub.2 and H.sub.4 respectively. After the third and seventh tracks 3' and 7' are finished playing, the head group H is descended again to the next lower level to play the fourth and eighth recording tracks 4' and 8' (Channel-4) through the heads H.sub.2 and H.sub.4.
When a four-channel tape cartridge is inserted into the tape player, the multi-pole changeover switch SW.sub.1 is switched into the state opposite to that shown in FIG. 1 (not shown). Assuming that the head block H is at its highest level, signals recorded on the first, third, fifth and seventh recording tracks 1', 3', 5' and 7' are picked up respectively by the magnetic heads H.sub.1, H.sub.2, H.sub.3 and H.sub.4. When the full length of the tape is finished playing, the solenoid 2 is energized by the short-circuit of the contactor 3 to cause the head block H to descend to the next lower tape tracks. The signals recorded on the second, fourth, sixth and eighth recording tracks 2', 4', 6' and 8' are then played respectively by the magnetic heads H.sub.1, H.sub.2, H.sub.3 and H.sub.4. Thus, on every one round of the tape, the head block H is shifted up and down to play, respectively, each of the recording tracks in four-channel mode.
From the foregoing description, it is apparent that in a two-channel and four-channel cartridge tape player according to the prior art, a two-stepped head shifting cam, a switch SW.sub.3 related to the position of the head block H, a relay RY, and a changeover switch for amplifiers are provided to play two-channel cartridge as well as four-channel, which necessitates complicated construction and results in a less reliable operation. Furthermore, because two-channel cartridge tape players generally require a four-stepped head shifting cam, the employment of a two-stepped head shifting cam for four-channel cartridge play will bring inevitably about the changes in design of the tape player which increase the cost and the relative size of the tape player.